ABSTRACT: Current cyber network defense strategies often focus on treating all tasks or activities that support military missions as if they were of equal importance, thus requiring the same level of protection to mitigate the effects of potential cyber attacks. Clearly, this is not the case. Mission-supporting activities have different impacts on mission objectives and therefore must be prioritized. There is a need to alter the current defense focus from information assurance and perimeter defense (ensuring the successful transmission of information to the appropriate destinations) to mission assurance (ensuring the attainment of mission objectives). 21CT"s Network Prioritization Analysis Capability (NetPAC) is a holistic approach using system dynamics modeling to represent the activities supporting one or more Air Force missions. The model consists of key activities and interactions, feedback loops, and delays, all critical factors needed in analyzing mission assurance. The NetPAC Phase I technical effort resulted in the generation of an early prototype, paving the way for full implementation in Phase II. The system dynamics approach was shown to be feasible for addressing the Air Force objectives. In Phase II, we plan to enhance the capabilities of the system dynamics model by considering an entire spectrum of Air Force missions and supporting activities, the cyber services underlying these missions, and the software needed to facilitate data entry, model execution, and collaborative decision-making across military organizations. BENEFIT: When fully developed and deployed, NetPAC is expected to give military planners and commanders the ability to analyze missions, mission-supporting activities, and IT assets and services to determine the priorities that must be established to satisfy military objectives. NetPAC will provide a"what if"capability to support collaborative decision-making about mission and activity prioritization. The decisions will be at both the planning stage and the execution (real-time) stage of military missions.